Native IPv6 firewalling is only supported in kernel versions 2.4+. In older 2.2- you can only filter IPv6-in-IPv4 by protocol 41.
Attention: no warranty that described rules or examples can really protect your system!
Audit your ruleset after installation, see Section 18.3 for more.
Note also that the USAGI project is currently working on finishing the connection tracking for IPv6! This will make ruleset easier and more secure in the future!